1. Field of the Invention
The present invention relates to a vehicular lamp, and more specifically relates to a vehicular lamp that combines light radiated from a plurality of lamp units to form a predetermined light distribution pattern.
2. Related Art
Vehicular lamps must be able to form a high-precision light distribution pattern from a safety standpoint. Such a light distribution pattern is formed by an optical system that uses a reflecting mirror or a lens, for example. Vehicular lamps have also been proposed that combine light radiated from a plurality of lamp units to form a predetermined light distribution pattern (see Patent Document 1 for an example).
For the plurality of lamp units, this kind of vehicular lamp may use the following: a cut-off line forming unit, which radiates light for forming horizontal and oblique cut-off lines of a low-beam distribution pattern; a hot zone forming unit, which radiates light for forming a hot zone of the low-beam distribution pattern; and a diffusion area forming unit, which radiates light for forming a diffusion area of the low-beam distribution pattern. By suitably combining these three types of lamp units, it is possible to obtain a low-beam distribution pattern with a desired pattern formation and light intensity distribution.
A low-beam distribution pattern PL shown in FIG. 9 is a light distribution pattern for driving on the left-hand side, and has horizontal and oblique cut-off lines CL1, CL2 on an upper edge thereof. An elbow point E is set at a position about 0.5 to 0.6 degrees below H-V, which is a vanishing point in a lamp forward direction. A hot zone HZ that is a high light intensity area is formed so as to surround the elbow point E somewhat in the leftward direction. The low-beam distribution pattern PL is formed as a pattern synthesizing a cut-off line forming pattern Pa, a hot zone forming pattern Pb, and a diffusion area forming pattern Pc.
[Patent Document 1] U.S. Pat. No. 6,882,110